Mass Transfer Evaporation Method

Mass Transfer Evaporation Method. Prepared By: Joey Q. Dy (Group 6).

Mass Transfer. Mass transfer is the net movement of mass from one location, usually meaning stream, phase, fraction or component, to another. Mass transfer occurs in many processes, such as absorptio n, evaporation, drying, precipitation, membrane filtration, and distillatio n. Mass transfer is used by different scientific disciplines for different processes and mechanisms. Some common examples of mass transfer processes are the evaporation of water from a pond to the atmosphere, the purification 0f blood in the kidneys and liver, and the distillation of alcohol..

Mass Transfer Evaporation Method Formula. where ; uz= windspeed at some height z above the water surface, e0= saturation vapor pressure calculated from the temperature of the water surface, and e a=vapor pressure of the air. Various forms of the equation use different multiplier constants and different functions of wind speed based upon area, season, lake size, temperature and other factors..

Sample Study #1. Comparison of Evaporation Computation Methods, Pretty Lake, Lagrange County, Northeastern Indiana GEOLOGICAL SURVEY PROFESSIONAL PAPER 686-A.

Sample Study #1. The study of Pretty Lake assumed the mass-transfer relationship to be in the form developed in the Lake Hefner study (Marciano and Harbeck, 1952) as (11) which is the same equation used with equations 4 und 5 to estimate QA in the previous section. Here, N is a constant for a specific lake, and u, is the average wind speed measured 2 meters (6.56 ft.) above the water surface. Harbeck, realizing that the mass-transfer co- efficient, N, summarizes rnuny variables such as wind and vcpor profiles and wuve heights, has made an empirical relationshipt between the constant and the surface area, At of the body of woter to which it applies (Harbeck, 1962, fig. 31). The eon- stunt N can be only roughly related to lake size, for it also is tlffeeted by local peculiarities, topogrcphyt und lÄ)int of wind measurement, One purpose of the Pretty Lake study was to determine the tnas-transfer co- efficient and to compare the Pretty Lake coefficient with those of other lakes or with a coefficient of 0.00661 predicted by Harbeck's surface-area method..

Sample Study #2. EVAPORATION COMPUTED BY ENERGY' BUDGET AND MASS-TRANSFER METHODS AND WATER-BALANCE ESTIMATES FOR DEVILS NORTH PAKOTA 1986-88 BY Gregg J. Wiche Geologic.' Survey.

Sample Study #2. EVAPORATION COMPUTED BY MASS-TRANSFER METHOD Mass-Transfer Coefficient In this study, energy-budget evaporation was used as the independent measure of evaporation used to detemine the mass-transfer coefflclent (N). The relation of mass-transfer product CU2(eo-ea)] to energy-budget evaporation is shown fn figure 7. The linear regression equation developed and used to determine N, which is the slope of the line of best fit, is Emt 0.019+NU2(eo-ea). where N 0.0020 (14).

N generally is cmputed as the slope of a straight line (fig. 7) passing through the origin; in this study, however, a constant (y-lntercept) of 0.019 provides the best fit. The physical basis for having the straight line pass through the origin Is that when the wind is calm there is no vapor pressure gradient (eo-ea 0), and the turbulent exchange of vapor between the lake surface and the air is negligible. The asslnption is made that the independ- ent variable used to determine N is without error. However, error undoubtedly occurs in V2(eo-ea); thus, adding a constant to equation 9 provides the best estimate of mass-transfer evaporation frm Devils Lake. Equation 14 has a coefficient of determination of 0.73 and a standard error of estimate of 0.03 inch per day..

Source: https://en.wikipedia.org/wiki/Mass_transfer https://www.sciencedirect.com/science/article/pii/S0017931019341791 https://pubs.usgs.gov/pp/0686a/report.pdf https://www.swc.nd.gov/info_edu/reports_and_publications/pdfs/wr_investigations/wr11_report.pdf.